/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.sockjs.support;

import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.context.Lifecycle;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.http.server.ServletServerHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.CorsConfigurationSource;
import org.springframework.web.servlet.HandlerMapping;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.handler.ExceptionWebSocketHandlerDecorator;
import org.springframework.web.socket.handler.LoggingWebSocketHandlerDecorator;
import org.springframework.web.socket.sockjs.SockJsException;
import org.springframework.web.socket.sockjs.SockJsService;

/**
 * An {@link HttpRequestHandler} that allows mapping a {@link SockJsService} to requests
 * in a Servlet container.
 *
 * @author Rossen Stoyanchev
 * @author Sebastien Deleuze
 * @since 4.0
 */
public class SockJsHttpRequestHandler
        implements HttpRequestHandler, CorsConfigurationSource, Lifecycle, ServletContextAware {

    // No logging: HTTP transports too verbose and we don't know enough to log anything of value

    private final SockJsService sockJsService;

    private final WebSocketHandler webSocketHandler;

    private volatile boolean running = false;


    /**
     * Create a new SockJsHttpRequestHandler.
     *
     * @param sockJsService the SockJS service
     * @param webSocketHandler the websocket handler
     */
    public SockJsHttpRequestHandler(SockJsService sockJsService, WebSocketHandler webSocketHandler) {
        Assert.notNull(sockJsService, "SockJsService must not be null");
        Assert.notNull(webSocketHandler, "WebSocketHandler must not be null");
        this.sockJsService = sockJsService;
        this.webSocketHandler =
                new ExceptionWebSocketHandlerDecorator(new LoggingWebSocketHandlerDecorator(webSocketHandler));
    }


    /**
     * Return the {@link SockJsService}.
     */
    public SockJsService getSockJsService() {
        return this.sockJsService;
    }

    /**
     * Return the {@link WebSocketHandler}.
     */
    public WebSocketHandler getWebSocketHandler() {
        return this.webSocketHandler;
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        if (this.sockJsService instanceof ServletContextAware) {
            ((ServletContextAware) this.sockJsService).setServletContext(servletContext);
        }
    }


    @Override
    public void start() {
        if (!isRunning()) {
            this.running = true;
            if (this.sockJsService instanceof Lifecycle) {
                ((Lifecycle) this.sockJsService).start();
            }
        }
    }

    @Override
    public void stop() {
        if (isRunning()) {
            this.running = false;
            if (this.sockJsService instanceof Lifecycle) {
                ((Lifecycle) this.sockJsService).stop();
            }
        }
    }

    @Override
    public boolean isRunning() {
        return this.running;
    }


    @Override
    public void handleRequest(HttpServletRequest servletRequest, HttpServletResponse servletResponse)
            throws ServletException, IOException {

        ServerHttpRequest request = new ServletServerHttpRequest(servletRequest);
        ServerHttpResponse response = new ServletServerHttpResponse(servletResponse);

        try {
            this.sockJsService.handleRequest(request, response, getSockJsPath(servletRequest), this.webSocketHandler);
        } catch (Throwable ex) {
            throw new SockJsException("Uncaught failure in SockJS request, uri=" + request.getURI(), ex);
        }
    }

    private String getSockJsPath(HttpServletRequest servletRequest) {
        String attribute = HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE;
        String path = (String) servletRequest.getAttribute(attribute);
        return (path.length() > 0 && path.charAt(0) != '/' ? "/" + path : path);
    }

    @Override
    @Nullable
    public CorsConfiguration getCorsConfiguration(HttpServletRequest request) {
        if (this.sockJsService instanceof CorsConfigurationSource) {
            return ((CorsConfigurationSource) this.sockJsService).getCorsConfiguration(request);
        }
        return null;
    }

}
